This link from Donovan Strain has been making the rounds where he puts together an analysis of Ice Cube's It Was A Good Day to try and determine the actual date of said Good Day. He pegged it as January 20th, 1992.

lahatiel followed up with some corrections on tumblr that (probably correctly) changed it to November 30th, 1988.

Strain's analysis (and to a lesser extent, lahatiel's) uses the reference to Cube being beeped and an assumption about availability of those beepers as a major factor in determining the date of the song's events, arguing that beepers weren't generally available before the late 80s or early 90s. Considering that this is a deep technical analysis of a rap lyric I'm pretty surprised that neither of them were familiar enough with the Beastie Boys The New Style to remember their 1986 line from License To Ill: